Summer is peak season for ticks and mosquitoes, and the insects may pose a particularly acute threat this year, experts say. On Monday, the Centers for Disease Control and Prevention issued an alert about the first locally acquired malaria cases in the United States in 20 years, detected in Florida and Texas.
Mosquitoes thrive in hot, humid conditions, so the season’s high temperatures aren’t helping: Scorching heat is blanketing Texas, with heat warnings and advisories in effect for a dozen states. TO report released last month of the research organization Climate Central found that the number of annual «mosquito days,» defined as days with an average relative humidity of 42% or higher and temperatures of 50 to 95 degrees Fahrenheit, has increased since 1979 by more than 70%. of the US locations studied.
“A lot of work went into eradicating malaria from the US in the 20th century, which involved a lot of things that might not have been friendly to the environment,” said Dr. Ryan Miller, an infectious disease specialist at the Cleveland Clinic. «But having it reintroduced to the US raises a red flag.»
The risk of contracting malaria in the US remains low. But mosquitoes can also transmit West Nile virus, which can cause fever, headache, body aches, vomiting, diarrhea or a rash, although 8 out of 10 people who get it don’t develop symptoms. According to the Centers for Disease Control and Prevention. He registered agency more than 1,100 cases last year, although the number of cases has hovered near 2,000 a year for the past decade.
Meanwhile, tick season is usually worst from late May to early July. Experts say they have observed tick populations expanding beyond rural areas and into cities in recent years.
He CDC estimates About 476,000 people a year contract Lyme disease, the most common threat from ticks. But other less common tick-borne diseases, including babesiosis and Rocky Mountain spotted feverhave seen the number of cases in the US rise in the past decade.
Miller said that as temperatures rise due to climate change, the threats from ticks and mosquitoes become less seasonal.
“Unfortunately, with a fairly warm and mild winter, tick and mosquito seasons have already arrived,” Miller said. “We have had cases of Lyme disease even in the spring, which is a little more unusual, and some people even in the late fall of last year. It seems like this year, it’s going to be all year.»
Tracking Mosquito-borne Diseases in the US
The CDC had registered 385 cases of dengue, another mosquito-borne disease, in the US as of June 1. More than 250 of those infections occurred in Puerto Rico; in a last month’s articlethe agency urged more action to control the spread of dengue in US territories.
As of Tuesday, the CDC had confirmed 17 cases of West Nile virus, seven of which were in Arizona. The highest-risk months for the virus are yet to come, according to Graham McKeen, university assistant director for environmental and public health at Indiana University.
McKeen said the Aedes aegypti mosquito, which transmits dengue and Zika viruses, has become increasingly common in the South and Southwest during the last decade.
“We are seeing them in new areas where they weren’t found before,” he said. «Our kind of extensive use of pesticides over many decades has also led to increased pesticide resistance in mosquitoes.»
McKeen added that people can still take «tried and true» precautions, such as wearing insect repellent and long-sleeved clothing and pants.
“Try to remove any standing or standing water on or around your property,” he said.
A mild winter can mean more ticks
This year’s mild winter has led to more cases of tick-borne infections than usual, particularly Lyme disease, according to Maria Diuk-Wasser, a vector-borne disease specialist and professor at Columbia University.
“The rising cases are usually in new regions that didn’t have it before, so from what we’re seeing in Maine, Ohio and Michigan, a lot of northern states, it’s going up a lot,” Diuk-Wasser said. “We are all reporting a very high year.”
Adult ticks are most active in the spring, but adolescent ticks in the summer are more dangerous, Diuk-Wasser added, because these nymphal ticks are about the size of a poppy seed. That makes them hard to spot even after they bite.
To protect yourself, she recommended washing clothes right away or at least putting the items in the dryer after spending time outdoors. People should also continue to check for ticks in the days that follow, as a nymphal tick may grow larger and be easier to spot.
The ticks may be invading cities including Austin, Texas, Chicago, New York and Pittsburgh, Diuk-Wasser added. Her lab has been studying how migratory deer (known as tick hosts) have been introducing the insects into parts of New York City, particularly parks and outdoor areas in Queens.
In collaboration with several other universities, the Diuk-Wasser lab helps run tick applicationa tool that allows users to submit a picture of the tick that bit them to get more information, including whether it is the blacklegged tick that carries Lyme disease.
“We still need to enjoy the outdoors and really preserve all the green spaces that we have in the cities, so we don’t have to be afraid of ticks,” Diuk-Wasser said. “We just have to protect ourselves and be aware.”